Allylamine → Tert-butyl 2-(allylcarbamoyl)-4-(2,2-difluoroethyl)-1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate

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Reaction Steps

To 9-(tert-butoxycarbonyl)-4-(2,2-difluoroethyl)-1-oxa-4,9-diazaspiro[5.5]undecane-2-carboxylic acid (520 mg, 1.43 mmol), prop-2-en-1-amine (118 μL, 1.57 mmol) and T3P (2.12 mL of 50% w/w, 3.59 mmol) in 2-methyltetrahydrofuran (4 mL) was added triethylamine (597 μL, 4.28 mmol) at room temperature and the reaction mixture was stirred for 2 hours. The reaction mixture was then quenched with saturated NaHCO3 solution (3 mL) and stirred for an additional 10 minutes, then diluted with EtOAc and the layers were separated. The aqueous layer was extracted once more with EtOAc, and the combined organics were dried over Na2SO4, filtered and concentrated in vacuo to an oil. The residue was purified by silica gel column chromatography using 0-50% EtOAc in hexanes to yield tert-butyl 2-(allylcarbamoyl)-4-(2,2-difluoroethyl)-1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate (480 mg, 83%). ESI-MS m/z calc. 403.2. found 404.5 (M+1)+; Retention time: 1.78 minutes (3 min run).

Provenance & Evidence